Carbon atoms of carbon materials are in an irregular arrangement, and only by subjecting the carbon atoms to a high temperature treatment of 2200˜2600° C. to make the carbon atoms re-crystallize and orderly rearrange can the carbon materials present the crystal structure of graphite and have many fine performances of graphite. For example, the conductivity and thermal conductivity are improved obviously, the chemical and thermal stabilities become better, the impurities are decreased, the hardness is reduced, the machining properties become better, etc. The function of graphitizing furnace is to convert carbon materials into man-made graphite materials, for example, graphite materials providing excellent carbon elements for steel smelting, aluminum smelting, cathode material, other non-ferrous metal industries, and nuclear industry, etc.
Currently, the most widely used graphitizing furnace is Acheson furnace. The Acheson furnace has an open rectangular furnace body structure. During production, the carbon materials are arranged longitudinally or transversely, and metallurgical coke and quartz sand are filled around them. Power is supplied along the length direction of the furnace body, and heat is generated utilizing the resistance of the coke, and finally the heated objects generate resistance and generate heat; lining materials such as coke powder, carbon black, a mixture of silica sand/coke/silicon carbide, are used for heat shielding around the coke for heat insulation.
Main shortcomings of the current Acheson furnace are as follows:
1. The Acheson furnace has a horizontal and open structure, so it has serious heat consumption. The variable unit consumption of the electrical energy consumption is 20-40 GJ/T and the product purity is not high.
2. The cooling period of the furnace body lasts long. The graphitizing process takes 2-7 days by heating of electricity, but it takes about two weeks to cool large amounts of coke filler, and performing forced cooling by spraying water brings much pollution to the environment and the efficiency is low.
3. The product is not heated uniformly. The temperature at the center of the product reaches 2600° C., while the peripheral temperature is only about 1000C., which results in non-uniform graphitization and unstable quality of the product.
4. Sulfur dioxide gas emitted during a high temperature process cannot be collected and treated, which results in environmental pollution.
In view of the above discussion, the Acheson furnace of the prior art cannot meet the demands of energy saving and emission reducing, operation safety and stability of product quality.